1. Field of the Invention
The present invention relates to a process for producing a specific aminosilane compound, which is effective particularly in industrial production.
2. Description of the Related Arts
Aminosilane compounds containing a group having a cyclopentadiene skeleton are recently attractive as ligands for various transition metal complexes, or the like. The transition metal complexes having these ligands are effective in many reactions for organic synthesis. Among them, specific complexes of early transition metals such as titanium, zirconium or the like are extremely effective as components for olefin polymerization of olefins and are being widely studied including their practical application. (e.g. WO 93/08199, U.S. Pat. No. 5,096,867).
Synthesis of these aminosilane compounds containing a group having a cyclopentadiene skeleton is usually conducted by a three-step reaction in which respective starting compounds for three parts (i.e., a part for a group having a cyclopentadiene skeleton, a part for an amino group and a part for a silane skeleton) of these compounds are joined together. Thus, they are usually synthesized by first reacting a compound having a cyclopentadiene skeleton with an organic alkali metal compound such as methyl lithium, n-butyl lithium or the like in the presence of a solvent such as hexane or the like to synthesize an alkali metal salt of the compound having a cyclopentadiene skeleton, removing an excess organic alkali metal compound by isolation by filtration/drying, and then reacting the salt with a chlorinated silyl compound, further reacting the isolated reaction product with an amine or its alkali metal salt (e.g. JP-A-7-53618, JP-A-5-505593, WO 93/08221) The yield in the conventionally known synthetic process, however, is not completely satisfactory.
The process in which a compound having a cyclopentadiene skeleton is reacted with an organic alkali metal compound such as methyl lithium, n-butyl lithium or the like synthesize an alkali metal salt of the compound having a cyclopentadiene skeleton is generally performed by a process described by C. M. Fendrick et al. In Organometallics, No. 3, page 819 (1984) or others, and uses as a solvent hexane or the like which is a solvent for commercially available organic alkali metal compounds.
Generally, the alkali metal salts of the compound having a cyclopentadiene skeleton are very sensitive to the air. Therefore, industrial performance of isolation treatment for the alkali metal salts of the compound having a cyclopentadiene skeleton had a considerable number of problems such as combustion by contacting with air, difficulty of stirring in the reaction system without the large amount of solvent and extreme decrease in filtering efficiency, due to a great increase in volume in the aliphatic solvent such as hexane and the like.
In addition, while the synthesis of the alkali metal salts of the compound having a cyclopentadiene skeleton has been carried out at a temperature of about -78.degree. C. in a laboratory scale in many cases, the reaction in the industrial scale at a low temperature at about -78.degree. C. requires much economical burden. Furthermore, there are many restrictions for the apparatus to be used and quality thereof. Therefore, a need exists for the establishment of a reaction technique that allows the performance of the reaction at an industrially advantageous temperature range of -20.degree. C. or above.